const reader = require("readline").createInterface({
  input: process.stdin,
  output: process.stdout
});
let lines = [];
reader.on("line", line => {
  lines.push(line);
});
reader.on("close", () => {
  const newArr = lines[0].split(' ').map(str => parseInt(str, 10))
  if (newArr[2] >= newArr[1]) {
    console.log(newArr[2] - 2)
  } else if (newArr[2] < newArr[1]) {
    console.log(newArr[2] - 1)
  } else if (newArr[2] <= newArr[0]) {
    console.log(0)
  }
});